<title>挖水井</title><link href="http://hzoi.com/tomorrow.css" rel="stylesheet"><div class="ui existing segment"><pre><code><span class="pl-cp">#include</span> <span class="pl-cpf">&lt;iostream&gt;</span><span class="pl-cp"></span>
<span class="pl-cp">#include</span> <span class="pl-cpf">&lt;cstdio&gt;</span><span class="pl-cp"></span>
<span class="pl-cp">#include</span> <span class="pl-cpf">&lt;cstring&gt;</span><span class="pl-cp"></span>
<span class="pl-cp">#include</span> <span class="pl-cpf">&lt;algorithm&gt;</span><span class="pl-cp"></span>
<span class="pl-k">using</span> <span class="pl-k">namespace</span> <span class="pl-n">std</span><span class="pl-p">;</span>
<span class="pl-k">struct</span> <span class="pl-n">Edge</span><span class="pl-p">{</span>
    <span class="pl-kt">int</span> <span class="pl-n">qs</span><span class="pl-p">,</span> <span class="pl-n">zz</span><span class="pl-p">,</span> <span class="pl-n">w</span><span class="pl-p">;</span>
    <span class="pl-kt">bool</span> <span class="pl-k">operator</span><span class="pl-o">&lt;</span><span class="pl-p">(</span><span class="pl-n">Edge</span> <span class="pl-n">b</span><span class="pl-p">)</span><span class="pl-k">const</span><span class="pl-p">{</span><span class="pl-k">return</span> <span class="pl-n">w</span> <span class="pl-o">&lt;</span> <span class="pl-n">b</span><span class="pl-p">.</span><span class="pl-n">w</span><span class="pl-p">;}</span>
<span class="pl-p">}</span> <span class="pl-n">E</span><span class="pl-p">[</span><span class="pl-mi">100000</span><span class="pl-p">];</span>
<span class="pl-kt">long</span> <span class="pl-kt">long</span> <span class="pl-n">f</span><span class="pl-p">[</span><span class="pl-mi">1000</span><span class="pl-p">],</span> <span class="pl-n">ans</span> <span class="pl-o">=</span> <span class="pl-mi">0</span><span class="pl-p">,</span> <span class="pl-n">k</span> <span class="pl-o">=</span> <span class="pl-mi">0</span><span class="pl-p">,</span> <span class="pl-n">n</span><span class="pl-p">,</span> <span class="pl-n">m</span><span class="pl-p">,</span> <span class="pl-n">w</span><span class="pl-p">[</span><span class="pl-mi">1000</span><span class="pl-p">],</span> <span class="pl-n">jl</span><span class="pl-p">[</span><span class="pl-mi">1000</span><span class="pl-p">];</span>
<span class="pl-kt">int</span> <span class="pl-nf">find</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">x</span><span class="pl-p">){</span><span class="pl-k">return</span> <span class="pl-n">x</span> <span class="pl-o">==</span> <span class="pl-n">f</span><span class="pl-p">[</span><span class="pl-n">x</span><span class="pl-p">]</span> <span class="pl-o">?</span> <span class="pl-nl">x</span> <span class="pl-p">:</span> <span class="pl-p">(</span><span class="pl-n">f</span><span class="pl-p">[</span><span class="pl-n">x</span><span class="pl-p">]</span> <span class="pl-o">=</span> <span class="pl-n">find</span><span class="pl-p">(</span><span class="pl-n">f</span><span class="pl-p">[</span><span class="pl-n">x</span><span class="pl-p">]));}</span>
<span class="pl-kt">void</span> <span class="pl-nf">join</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">x</span><span class="pl-p">,</span> <span class="pl-kt">int</span> <span class="pl-n">y</span><span class="pl-p">){</span><span class="pl-n">f</span><span class="pl-p">[</span><span class="pl-n">find</span><span class="pl-p">(</span><span class="pl-n">x</span><span class="pl-p">)]</span> <span class="pl-o">=</span> <span class="pl-n">find</span><span class="pl-p">(</span><span class="pl-n">y</span><span class="pl-p">);}</span>
<span class="pl-kt">int</span> <span class="pl-nf">main</span><span class="pl-p">(){</span>
    <span class="pl-n">cin</span> <span class="pl-o">&gt;&gt;</span> <span class="pl-n">n</span><span class="pl-p">;</span>
    <span class="pl-k">for</span> <span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">i</span> <span class="pl-o">=</span> <span class="pl-mi">1</span><span class="pl-p">;</span> <span class="pl-n">i</span> <span class="pl-o">&lt;=</span> <span class="pl-n">n</span><span class="pl-p">;</span> <span class="pl-o">++</span><span class="pl-n">i</span><span class="pl-p">)</span><span class="pl-n">scanf</span><span class="pl-p">(</span><span class="pl-s">&quot;%lld&quot;</span><span class="pl-p">,</span> <span class="pl-o">&amp;</span><span class="pl-n">w</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">]);</span>
    <span class="pl-k">for</span> <span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">i</span> <span class="pl-o">=</span> <span class="pl-mi">1</span><span class="pl-p">;</span> <span class="pl-n">i</span> <span class="pl-o">&lt;=</span> <span class="pl-n">n</span> <span class="pl-o">+</span> <span class="pl-mi">1</span><span class="pl-p">;</span> <span class="pl-o">++</span><span class="pl-n">i</span><span class="pl-p">)</span><span class="pl-n">f</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">]</span> <span class="pl-o">=</span> <span class="pl-n">i</span><span class="pl-p">;</span>
    <span class="pl-k">for</span> <span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">i</span> <span class="pl-o">=</span> <span class="pl-mi">1</span><span class="pl-p">;</span> <span class="pl-n">i</span> <span class="pl-o">&lt;=</span> <span class="pl-n">n</span><span class="pl-p">;</span> <span class="pl-o">++</span><span class="pl-n">i</span><span class="pl-p">)</span>
        <span class="pl-k">for</span> <span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">j</span> <span class="pl-o">=</span> <span class="pl-mi">1</span><span class="pl-p">;</span> <span class="pl-n">j</span> <span class="pl-o">&lt;=</span> <span class="pl-n">n</span><span class="pl-p">;</span> <span class="pl-o">++</span><span class="pl-n">j</span><span class="pl-p">){</span>
            <span class="pl-kt">int</span> <span class="pl-n">x</span><span class="pl-p">;</span>
            <span class="pl-n">scanf</span><span class="pl-p">(</span><span class="pl-s">&quot;%d&quot;</span><span class="pl-p">,</span> <span class="pl-o">&amp;</span><span class="pl-n">x</span><span class="pl-p">);</span>
            <span class="pl-k">if</span> <span class="pl-p">(</span><span class="pl-n">x</span> <span class="pl-o">!=</span> <span class="pl-mi">0</span><span class="pl-p">){</span>
                <span class="pl-n">E</span><span class="pl-p">[</span><span class="pl-o">++</span><span class="pl-n">m</span><span class="pl-p">].</span><span class="pl-n">qs</span> <span class="pl-o">=</span> <span class="pl-n">i</span><span class="pl-p">;</span>
                <span class="pl-n">E</span><span class="pl-p">[</span><span class="pl-n">m</span><span class="pl-p">].</span><span class="pl-n">zz</span> <span class="pl-o">=</span> <span class="pl-n">j</span><span class="pl-p">;</span>
                <span class="pl-n">E</span><span class="pl-p">[</span><span class="pl-n">m</span><span class="pl-p">].</span><span class="pl-n">w</span> <span class="pl-o">=</span> <span class="pl-n">x</span><span class="pl-p">;</span>
            <span class="pl-p">}</span>
        <span class="pl-p">}</span>
    <span class="pl-k">for</span> <span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">i</span> <span class="pl-o">=</span> <span class="pl-mi">1</span><span class="pl-p">;</span> <span class="pl-n">i</span> <span class="pl-o">&lt;=</span> <span class="pl-n">n</span><span class="pl-p">;</span> <span class="pl-o">++</span><span class="pl-n">i</span><span class="pl-p">){</span>
        <span class="pl-n">E</span><span class="pl-p">[</span><span class="pl-o">++</span><span class="pl-n">m</span><span class="pl-p">].</span><span class="pl-n">qs</span> <span class="pl-o">=</span> <span class="pl-n">i</span><span class="pl-p">;</span>
        <span class="pl-n">E</span><span class="pl-p">[</span><span class="pl-n">m</span><span class="pl-p">].</span><span class="pl-n">zz</span> <span class="pl-o">=</span> <span class="pl-n">n</span> <span class="pl-o">+</span> <span class="pl-mi">1</span><span class="pl-p">;</span>
        <span class="pl-n">E</span><span class="pl-p">[</span><span class="pl-n">m</span><span class="pl-p">].</span><span class="pl-n">w</span> <span class="pl-o">=</span> <span class="pl-n">w</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">];</span>
        <span class="pl-n">E</span><span class="pl-p">[</span><span class="pl-o">++</span><span class="pl-n">m</span><span class="pl-p">].</span><span class="pl-n">qs</span> <span class="pl-o">=</span> <span class="pl-n">n</span> <span class="pl-o">+</span> <span class="pl-mi">1</span><span class="pl-p">;</span>
        <span class="pl-n">E</span><span class="pl-p">[</span><span class="pl-n">m</span><span class="pl-p">].</span><span class="pl-n">zz</span> <span class="pl-o">=</span> <span class="pl-n">i</span><span class="pl-p">;</span>
        <span class="pl-n">E</span><span class="pl-p">[</span><span class="pl-n">m</span><span class="pl-p">].</span><span class="pl-n">w</span> <span class="pl-o">=</span> <span class="pl-n">w</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">];</span>
    <span class="pl-p">}</span>
    <span class="pl-n">sort</span><span class="pl-p">(</span><span class="pl-n">E</span> <span class="pl-o">+</span> <span class="pl-mi">1</span><span class="pl-p">,</span> <span class="pl-n">E</span> <span class="pl-o">+</span> <span class="pl-n">m</span> <span class="pl-o">+</span> <span class="pl-mi">1</span><span class="pl-p">);</span>
    <span class="pl-kt">int</span> <span class="pl-n">k</span> <span class="pl-o">=</span> <span class="pl-mi">0</span><span class="pl-p">;</span>
    <span class="pl-k">for</span> <span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">j</span> <span class="pl-o">=</span> <span class="pl-mi">1</span><span class="pl-p">;</span> <span class="pl-n">j</span> <span class="pl-o">&lt;=</span> <span class="pl-n">m</span><span class="pl-p">;</span> <span class="pl-o">++</span><span class="pl-n">j</span><span class="pl-p">){</span>
        <span class="pl-k">if</span> <span class="pl-p">(</span><span class="pl-n">find</span><span class="pl-p">(</span><span class="pl-n">E</span><span class="pl-p">[</span><span class="pl-n">j</span><span class="pl-p">].</span><span class="pl-n">qs</span><span class="pl-p">)</span> <span class="pl-o">!=</span> <span class="pl-n">find</span><span class="pl-p">(</span><span class="pl-n">E</span><span class="pl-p">[</span><span class="pl-n">j</span><span class="pl-p">].</span><span class="pl-n">zz</span><span class="pl-p">)){</span>
            <span class="pl-n">join</span><span class="pl-p">(</span><span class="pl-n">E</span><span class="pl-p">[</span><span class="pl-n">j</span><span class="pl-p">].</span><span class="pl-n">qs</span><span class="pl-p">,</span> <span class="pl-n">E</span><span class="pl-p">[</span><span class="pl-n">j</span><span class="pl-p">].</span><span class="pl-n">zz</span><span class="pl-p">);</span>
            <span class="pl-n">ans</span> <span class="pl-o">+=</span> <span class="pl-n">E</span><span class="pl-p">[</span><span class="pl-n">j</span><span class="pl-p">].</span><span class="pl-n">w</span><span class="pl-p">;</span>
            <span class="pl-n">k</span><span class="pl-o">++</span><span class="pl-p">;</span>
        <span class="pl-p">}</span>
        <span class="pl-k">if</span> <span class="pl-p">(</span><span class="pl-n">k</span> <span class="pl-o">==</span> <span class="pl-n">n</span><span class="pl-p">)</span><span class="pl-k">break</span><span class="pl-p">;</span>
    <span class="pl-p">}</span>
    <span class="pl-n">cout</span> <span class="pl-o">&lt;&lt;</span> <span class="pl-n">ans</span><span class="pl-p">;</span>
    <span class="pl-k">return</span> <span class="pl-mi">0</span><span class="pl-p">;</span>
<span class="pl-p">}</span>
</cpde></pre></div>